If you guess the ending of HBO's 'Game of Thrones,' you could win a trip to Croatia

As the eighth and final season of HBO's "Game of Thrones " gets underway (Sunday's premiere hit record viewership), fans have been guessing how the popular show will end.

Those who believe they know could win a trip to Croatia if they're right.

Luxury tour company Unforgettable Croatia is giving away a seven-night trip to Split and Dubrovnik to see "Game of Thrones" filming locations. The catch is you have to correctly guess the how the HBO series ends to be in the running.

Croatia is home to many of the show's most famous filming locations and landmarks, like King's Landing (which is filmed in capital Dubrovnik), Slaver's Bay (filmed in the island of Hvar) and Meereen (filmed in the town of Split). Tourism there has soared since the show began in 2011.

The "luxury," "custom trip" across Croatia for two will take place in October and will include English-speaking guided "Game of Thrones" tours in Split (three nights) and Dubrovnik (four nights). The trip also includes five-star accommodations, a speed boat trip to the islands of Hvar and Vis and private transfers. However, international flights and other expenses are not included. (October flights from New York City to Dubrovnik currently start around $569, and $619 from Los Angeles.)

To enter, fans must send their prediction about how "Game of Thrones" will end. "The main thing we are looking for is for competition entrants to predict how the main characters will end," a rep from Unforgettable Croatia tells CNBC Make It. "What will happen to Jon Snow, Daenerys, Cersei, Tyrion and ultimately the White Walkers? We're not looking for an extensive answer but someone who is close enough to predicting how it finishes."

Unforgettable Croatia's website also suggests answering questions like: What character will end up on the Iron Throne? Will Danearys reunite Westeros with her dragons? And will John Snow kill Danaerys to ignite the Lightbringer sword?

However its official rules note, "the winner is at the full discretion of Unforgettable Croatia. The decision of Unforgettable Croatia is final and no correspondence will be entered into." If no one is "correct," "we will pick our favorite suggestion," according to the rules.

The contest website has information on how to enter and additional rules. Entries must be submitted by May 5. The "Game of Thrones" season finale airs on May 19. The contest has no affiliation with HBO.